Process for producing liquid np fertilizers

ABSTRACT

Phosphoric acid, containing polyphosphoric acid components, and nitric acid are concurrently and continuously reacted with a deficiency of ammonia under high turbulent conditions to vaporize water in the reacting mixture and to expel the latter from a reaction chamber after a brief retention period; the expelled mixture is quenched by air cooling and thereafter reacted with further ammonia to near-neutrality.

United States Patent [191 Austin Jan. 9, 1973 [54] PROCESS FOR PRODUCINGLIQUID NP FERTILIZERS FOREIGN PATENTS OR APPLICATIONS 632,617 12/1961Canada ..7l/35 [75] Inventor: James Austin, Horley, England 695,78110/1964 Canada ..71/36 Assigneez occidental Research & Engineering388,417 2/1933 Great Britain ..7l/35 Limited, London, England OTHERPUBLICATIONS [22] Filed: Apruzt 1969 Concentration of Wet Process Acidto Obtain Self 2 App] 12 0 sequestering Properties Siegel, June 11, 1959Pg. 30

Primary Examiner-Samih N. Zaharna [52] US. Cl ..7l/35, 71/36 AssistantExaminerfimchard Barnes [51] Int. Cl. ..C05b 7/00 Attome wmiam N Patrick[58] Field of Search ..7l/35, 36, 43; 23/107, 103 y [56] ReferencesCited [57] ABSTRACT UNITED STATES PATENTS Phosphoric acid, containingpolyphosphorlc acid components, and nitric acid are concurrently andcontinu- 3,537,814 11/1970 Farr et al. ..7l/43X ously reacted with adeficiency of ammonia under 3,459,499 8/1969 Mullen high turbulentconditions to vaporize water in the fi g a reacting mixture and to expelthe latter from a reac- 3:244:500 4/1966 Stinson g alnjm 71/43 x tionchamber after a brief retention period, the ex- 3,301,657 1/1967 Deeetal. ..71/43 Pelled mlXture 1S quenched y wolmg and 3,336,127 8/1967I'Iignett et a1... ..71/34 thereafter reacted with further ammonia tonear- 3,382,059 5/1968 Getzinger .71/43 X neutrality. 3,464,808 9/1969Kearns 71/43 X 3,492,087 1/1970 MacGregor et al ..71/43 X 4 Claims, 3Drawing Figures [646770/1/ VESSGL /.5

6 7 \l. 5 (OOH/V6 42 E6CE/V/A/6 VESSGL l 1 29 pH M6765 (WA/75964 ffPROCESS FOR PRODUCING LIQUID NP FERTILIZERS This invention relates tothe ammoniation of phosphoric acid and the production of liquidfertilizers containing the plant foods P and nitrogen. More particularlythe invention relates to the ammoniation of phosphoric acid containingpolyphosphoric acid components in a manner such as to minimizehydrolysis of the polyphosphoric acids while contemporaneouslyammoniating nitric acid thereby to produce a liquid containing the saidplant foods in selected proportions.

Phosphoric acid and superphosphoric acid (the latter containingpolyphosphoric acid components) have been ammoniated in the past byfeeding ammonia to an aqueous solution of the acid, accompanied bystirring and cooling to 180F. or lower temperatures in order to preventhydrolysis of the polyphosphoric acid components of the acid and theloss of ammonia which begins to bubble out of the solution at atemperature of about 180F. Phosphoric acid containing 83 percent P 0(superphosphoric acid) has been employed in an ammoniation process toproduce 11-37-0 (11 percent by weight nitrogen, 37 percent by weight P 0and 0 percent K 0, potash) grade liquid. That process involved dilutionof the 83 percent P 0 acid to 80-81 percent P 0 followed by the additionof ammonia and the dissipation of heat by evaporation of water. Theammoniation process was conducted in a solution kept at the boilingpoint of the 11-370 liquid (about 217F.). After ammoniation the productwas cooled to 100F by cooling coils or similar means. In this prior artmethod the diluted acid was ammoniated in 20 minutes to produce the11-37-0 liquid. At the temperature of 2l7F., some loss of ammonia wasindicated by the odor of the effluent gases, and reversion ofpolyphosphoric acids to orthophosphoric acid by hydrolysis wasconsiderable.

The above discussion indicates that there is a need for a process ofrapidly ammoniating phosphoric acid, especially phosphoric acidcontaining polyphosphoric acid components, which minimizes the loss ofpolyphosphoric acid components by hydrolysis during the ammoniationprocess. Such a process is one objective of the invention of co-pendingapplication Ser. No. 684,348 filed Nov. 20th, 1967 and now abandoned andof the continuation in part thereof, Ser. No. 785,321 filed Dec. 19th,1968, and now abandoned both assigned to my assignee.

The ammoniation of phosphoric acid to produce a liquid of near-neutralpH results in that liquid having an N:P O ratio of about 1:3, or ofslightly higher P 0 proportion in the case of ammoniating an acid havinga substantial polyphosphoric acid content that is not hydrolyzed in theammoniation. Often it is desired to produce a liquid having asubstantially different N:P O,-, ratio and hitherto this has involvedthe modification of the liquid produced by ammoniation of the acid bythe addition to that liquid of other components, for instance ammoniumnitrate and/or urea, a typical modification being the addition to -34-0grade ammonium phosphates solution of so-called nitrogen-base solutionof 35-0-0 grade, that is a solution of a mixture of ammonium nitrate andurea.

An objective of the present invention is to adapt the process andapparatus of the aforesaid application Ser.

No. 684,348 so as to enable the direct production of near-neutralliquids having N150, ratios higher than obtainable solely by theammoniation of phosphoric acids.

Accordingly, therefore, in one aspect the present invention provides aprocess that comprises introducing streams of water, ammonia, nitricacid and phosphoric acid containing polyphosphoric acid componentscontinuously into a reaction chamber for intermingling therein underconditions of high turbulence, the proportion of ammonia relative to theacids introduced into said chamber being less than that required forneutralization of the acids and the conditions being such that theintroduced ammonia is substantially totally reacted to produce a liquidreaction mixture and steam, withdrawing said reaction mixture and steamand separating the latter from the liquid, quenching said liquid andfinally reacting said liquid with ammonia in an amount to produce a nearneutral liquid product.

In this process the nitric acid and the phosphoric acid react with theammonia to produce, respectively, ammonium nitrate and ammoniumphosphates. By adjustment of the relative proportions of the respectiveacids the proportions of nitrate and phosphates in the final liquidproduct may be controlled so as to result in the latter having aselected N:P O ratio exceeding 123.5. It should be understood that inthe absence of the phosphoric acid feed the product would be an ammoniumnitrate solution having a N:P O ratio of 1:0.

The reactants may all be brought together simultaneously in the reactionchamber or, as is preferred, the nitric acid may be added downstream ofthe point of introduction of the ammonia, phosphoric acid and waterstreams, thereby to minimize hydrolysis of polyphosphoric acids by thenitric acid which will usually be introduced in the form of a 55 percentsolution.

The process may otherwise be performed as described in the aforesaidApplication; that is, the reactants may be caused to react in saidreaction chamber within a period ranging from 0.1 second to about 15minutes, the shorter periods within this range being preferredespecially when the reactants comprise a substantial proportion ofphosphoric acid having polyphosphoric acid components the hydrolysis ofwhich is to be minimized.

Likewise, the reaction is the reaction chamber may be performed attemperatures such as disclosed in said application, reactiontemperatures within the range ISO-350 F. being satisfactory but thereaction preferably being performed at a temperature within the range220-280 F.

The quenching step is preferably accomplished by countercurrent contactwith air, the liquid temperature being thereby reduced rapidly to withinthe range -150 F. Following the quenching step, the liquid may befurther cooled by indirect heat-exchange with one or more of thereactants, conveniently while being further ammoniated, and possiblydiluted with water, thereby to produce a final liquid product ofselected pH and specific gravity.

As in the case of the process described in said Application, the ammoniareactant may be liquid or gaseous at the point of entry to the reactionchamber.

The process of the invention may be performed in apparatus generally asdescribed in said application Ser. No. 684,348 but modified to enablethe extra reactant, nitric acid, to be introduced into the reactionchamber concurrently with the other reactants. Thus that apparatus maybe provided with an extra inlet for the nitric acid reactant, this inleteither being positioned to bring the nitric acid immediately intocontact with the other entering reactants or being positioned tointroduce the nitric acid into the reaction chamber so as to meet areacting mixture of the other reactants; the latter arrangement ispreferred. It should be understood that the nitric acid may be of anysuitable concentration. Usually a 55 percent aqueous solution will be aconvenient feedstock but, if desired, more or less of the required watermay be introduced as solvent for the nitric acid reactant, it beingunderstood that substantially all of the required water could beintroduced in this way, especially in the case in which the apparatushas its nitric acid inlet positioned to bring the introduced nitric acidinto immediate contact with the phosphoric acid and ammonia reactants.That is, the apparatus as described in the aforesaid Application couldbe used without modification beyond arranging for the feeding of anappropriate mixture of water and nitric acid to the reaction chamberthrough the inlet used, in the process described in said application,solely for water introduction.

The process of the invention will be further explained with reference toits performance in apparatus constructed and arranged as described inthe said application Ser. No. 684,348 and as illustrated in theaccompanying drawings, in which:

FIG. 1 is a schematic diagram;

FIG. 2 is a view partially in section of the reaction vessel of FIG. 1;and

FIG. 3 is a view, partially in section, of the reaction vessel, thecooling tower, the air blower and the reaction product receiving vessel.

Referring to the drawings, FIG. 1 represents, schematically, operationof a process in which either wet process or furnace phosphoric acid,anhydrous ammonia and aqueous nitric acid are admitted into a reactionvessel 1 through conduits 2, 3 and 4, respectively. Wet processphosphoric acids contain small amounts of iron and aluminum impuritiesas well as impurities of other substances found in phosphate bearingores. The phosphoric acid, which in the process of the present inventioncontains polyphosphoric acid components, is metered into the reactionvessel by conventional metering apparatus such as a metering pump ormagnetic flow meter, not shown. Ammonia reacts with the acids to formammonium phosphate, ammonium polyphosphates and ammonium nitrate withthe liberation of heat. The amount of water added to the reaction vesselis sufficient to keep the temperature of the reaction mixture within therange 65l 77C.

The heat liberated upon ammoniation of the acids is sufficient toconvert part of the water to steam.

The reaction. product mixture, including unammoniated acids, isdischarged through a conduit 5 into a cooling tower 6. The reactionproduct mixture is cooled in the tower 6 by contact with acountercurrent flow of air supplied by a blower 7. The air and watervapor are vented through a vent 8, together with any steam present inthe reaction product mixture coming from the reaction vessel 1. Thereaction product mixture which has been cooled to a temperature of fromabout 27C. to about C. is discharged through a reaction product outlet78 into a reaction product mixture receiving vessel 9.

The reaction product mixture can be transferred through conduits 10 and11 to storage either by gravity or with the aid of a pump 12. Should itbe desirable to lower the temperature of the reaction product, it may bepassed in heat-exchanging relationship with ammonia through aheat-exchanger l3.

Ammonia is fed in through inlet 14, heat exchanger 13, conduit 15, valve16, meter 17, and conduit 3 to the inlet to reaction vessel 1.

Water employed in the process is fed to the inlet of a conduit 30through a conduit 31, valve 32, meter 33 and conduit 4 to the reactionvessel 1.

The nitric acid employed in the process is also fed to the reactionvessel 1 via conduit 4, being introduced into the latter near itsconnection with vessel 1 through a suitable branch connection (notshown) to conduit 4, the amount of nitric acid being controlled bysuitable metering equipment (not shown) so as to maintain a chosenrelationship between the flows of the nitric and phosphoric acids to thevessel.

The ammonia and nitric and phosphoric acids can be admitted to thereaction vessel in the correct proportions to obtain a reaction producthaving the desired pI-I. Preferably, however, a portion of the reactionproduct is routed through a conduit 19, pH meter-controller 20 and aconduit 21 back to the receiving vessel 9. The pH meter-controllermonitors the. pH of the reaction product and provides an electricaloutlet signal of a phase and magnitude proportional to the direction anddegree of deviation of the measured pH from a predetermined pH set inthe instrument. Equipment for measuring the pH and providing a pHmetercontroller output signal is readily available commercially and willnot be further described here. A valve 99 in ammonia conduit 15 isactuated by valve actuator 22 in response to the output signal from thepH meter-controller 20 received through electrical conductor 23. Valveactuator 22 so controls the valve 99 as to increase or decrease the flowof ammonia therethrough so as to bring the pH of the reaction productback to the predetermined pH set on the pH meter-controller instrument.For example, when the pH is higher than the predetermined value, theopening of valve 99 is reduced thereby reducing the flow therethrough,which will have the effect of producing a reaction product with a lowerpH. On the other hand, if the pH is too low, valve actuator 22, inresponse to'the signalfrom the pH meter-controller, turns valve 99 toincrease the opening therethrough, allowing ammonia to flow throughconduit 15 at a higher rate to thereby provide a product with a higherpH.

Not all the ammonia required for neutralization of the acids is fed tothe reaction vessel 1 via conduit 3: up to about 30 percent of theammonia required is, instead, fed to the reaction product mixture inreceiving vessel 9 through a conduit 24, valve 25, meter 26 and conduit27. Valves 16 and 25 may be adjusted to permit, for example, aboutpercent of the ammonia used in the process to flow through conduit 3 tothe inlet to reaction vessel 1 and about percent to flow through meter26 and conduit 27 to the reaction product receiving vessel where thereaction product mixture is further ammoniated. The ammonia is bubbledinto the reaction product mixture through a sparger, not shown, locatednear the bottom of the vessel. The total amount of ammonia employed inthe process is controlled by the pH meter-controller 20.

A specific gravity indicatopcontroller 28 may, as shown, be mounted inconduit means 19 to monitor the specific gravity of the portion ofreaction product that is being circulated through conduit 19, pHmeter-controller and back to the receiving vessel 9 through conduit 21.The specific gravity indicator-controller monitors the specific gravityof the reaction product mixture and provides an electrical output signalto electrical conductor 29 of a phase and magnitude proportional to thedirection and degree of deviation of the specific gravity from thepredetermined specific gravity which has been set on the specificgravity indicator instrument. Equipment for measuring specific gravityand providing a specific gravity controller output signal, is readilyavailable commercially and will not be described here.

Valve 34 in conduit 31 is controlled by valve actuator 35 and controlsthe amount of water flowing through conduit 31. Valve controller 35 isresponsive to the output signal from specific gravityindicator-controller 28 and increases or decreases the opening of valve34 to as to permit that amount of water to flow therethrough which willprovide an end product having a predetermined specific gravity. Forexample, if the specific gravity is too low the valve controller 35 willdecrease the opening of valve 34 to permit less water to flowtherethrough, thereby increasing the density of the reaction product. Onthe other hand, if the specific gravity of the reaction product is toohigh, the valve controller 35, in response to the signal from thespecific gravity indicator-controller 28, will turn the valve 34 toincrease the opening therethrough, allowing more water to flow throughconduit 31 and thereby providing a product having a lower specificgravity.

All the water may be fed to the reaction vessel 1 via the conduit 4 or,as indicated some, e.g. up to about 30 percent, of the water flowingthrough control valve 34 may be routed through a conduit 36, valve 37,meter 38 and a conduit 39 to the receiving vessel 9. For example, thetotal amount of water employed in the process can be divided to providefor a flow of about 80 percent of such water through meter 33 to thereaction vessel 1 and 20 percent of the water through meter 38 andconduit 39 to the reaction product receiving vessel 9.

If desired, a portion of the reaction product mixture may berecirculated in heat-exchanging relationship with the water employed inthe process through a conduit 40, heat exchanger means 41, conduit 42,valve 43 and back to the receiving vessel means 9.

FIG. 2 shows a preferred form of the reaction vessel 1, having a fluidreceiving means 51 with one end thereof extending into the interior ofacolumn 72. The fluid receiving means 51 is equipped with inlet means 52,53 and 54 for phosphoric acid, ammonia and aqueous nitric acid,respectively. The fluid receiving means may be equipped with means forattaching pressure indicating devices and other instruments, as at 55.The

end portion of the fluid receiving means 51, which is encompassed by theclosed end 57 of the column 72, has a closed end 58 and a wall 56 with aplurality of apertures 59 providing communication between the interiorof the fluid receiving means 51 and the interior of the column 72. Thenumber and size of the apertures in the wall 56 depends on the capacityof the apparatus, that is, the volume of reaction mixture componentsrequired to pass therethrough per unit time. The aper-.

tures may be circular, square or any other desired shape. It is foundthat circular apertures having a diameter of from about one-sixteenthinch to about three-fourths inch, or higher, are satisfactory for theprocess of this invention. Circular apertures having a diameter of fromabout one-eighth to about threeeighths inch are preferred since theyimpart a good degree of mixing to the components fed to the fluidreceiving means as they pass therethrough. Especially preferred arecircular apertures having a diameter of one-fourth inch, as theseprovide a good mixing of product. The apertures can be spaced from aboutonefourth inch apart, in the case of apertures having a diameter ofone-eighth inch, to about 1% inches apart in the case of apertureshaving a diameter of threefourths inch. Apertures having a diameter ofonefourth inch can be spaced from about three-eighths to aboutthree-fourths inch apart. Apertures having a diameter of one-fourth inchdisposed about one-half inch apart in the walls of the end 56 of thefluid receiving means 51 are found to perform satisfactorily for theprocess of this invention.

The apertures 59 in wall 56 of the fluid receiving means 51, in diameterand number should be such as to provide a pressure drop for fluidpassing therethrough in the range of about 1 to about psi. It ispreferred that the pressure drop be within the range 2 to about 60 psifor thorough mixing of the components of the reaction mixture passingtherethrough.

The column 72 is composed of plurality of cylindrical sections 60 with aflange or other means at each end of a section such that the sectionsare adapted to being stacked and fastened together by means of bolts orother retaining means as shown in the drawing. The section 57 whichencompasses end 56 of the fluid receiving means 51 also has a flange orother means at the open end thereof adapted for mounting said fluidreceiving means 51 onto one end of the column 72. A plurality of platemembers 61 having a plurality of apertures in each, obturate the columnin spaced apart relationship. A plate member 61 is mounted in betweentwo sections of the column at a plurality of junctions of such pluralityof sections 60. The apertures 62 in the plates 61 can have the samecharacteristics as the apertures 59 in the wall 56 of fluid receivingmeans 51. When the apertures 62 are circular, the diameter thereof canvary from about one-sixteenth inch to about 1 inch. Apertures having adiameter of from about one-fourth to about three-fourths inch are foundto serve satisfactorily in providing a means for mixing the componentsmaking up the reaction mixture in this invention. Suitable packing 63 isdisposed between the plate members 61. The requirement of the packing isthat it provides for a mixing of the components passing therethrough inorder to enhance the efficiency of ammoniation of the acid. Suitablepacking material for example is A: to 2 inch stainless steel pipe cutinto sections of one-fourth inch to about 2 inches. Pall or Raschigpacking, berl, saddles, grid packing and spiral grids, are examples ofother packing material that can be employed. The material ofconstruction of equipment used in the process of this invention can beany corrosion resistant material such as, for example stainless steel.

FIG. 3 shows the preferred relationship between the reaction vessel 1,the cooling tower 6 and the receiving vessel 9. The reaction vessel 1 isconnected via connecting means 81 to a distributor 82 which extends intothe interior of the upper end of the cooling tower 6. The distributor 82is closed at its free end 83 and has a plurality of apertures 84 in itswalls providing communication between the interior of the distributorand the interior of the cooling tower. The apertures 84 can have thesame characteristics as the apertures 59 in the wall 56 of the fluidreceiving means 51. When the aper' tures 84 are circular, they have adiameter within the range from about one-sixteenth inch to about 3inches. Preferably, the diameters range from about one-eighth inch toabout 2 inches as apertures of this diameter function satisfactorily inthe process of this invention.

The cooling tower 6 has a vent 85 at its upper end to vent steam, watervapor and air. The lower end of the cooling tower has a reaction productoutlet 88 communicating with an inlet 98 to the reaction productreceiving vessel 9.

A de-entrainment means 86 is interposed between the distributor 82 andthe vent 85 to prevent any reaction product mixture from being carriedout of the vent. The blower 7 is connected to an inlet 87 near thebottom of the tower 6. Air is supplied in this manner for countercurrent heat exchange with the downward flowing reaction product mixturecoming from the reaction vessel 1 and flowing into the cooling towerthrough the apertures 84 in distributor 82. Suitable packing material(not shown) is disposed in the cooling tower between the distributor 82and the outlet 88. The packing material can be made up of sections ofstainless steel pipe from about one-fourth inch to about 2 inches inlength of from about one-fourth inch to about 3 inches in diameter, gridpacking or of other suitable packing material. The packing material isretained within the tower by a suitable retaining means (not shown) suchas a perforated plate or grate means or the like.

The receiving vessel 9 rests on support means 89. The bottom of thereaction product receiving vessel is indicated in dotted outline 90,showing an outlet 91 communicating with an outlet conduit 92.

The de-entrainment means 86 consists of material such as stainless steelwool, knitted polypropylene, polytetrafluorethylene or glass.Alternatively, the deentrainment means 86 may consist of a towerin'which gases ascend through a spiral path causing entrained reactionproduct mixture liquid to separate out and return downwardly to thecooling tower. Still other forms of de-entrainers are well known tothose skilled in the art.

The following Examples illustrate the process of the invention. InExample 1, the process was performed as described above inrelation toFIG. 1 and using a reaction vessel 1 as illustrated in FIG. 2; inExample 2, the

reaction vessel was a modified construction as will be explained.Example 1 In-this example the reactants and their proportions by weightwere as follows:

Phosphoric acid 93 (76% P,O,, 60% thereof as polyphosphoric acid) Nitricacid (55% solution HNO,) I87 Water 90 Ammonia (anhydrous) 50 Asdescribed the bulk of the water and all of the nitric acid were mixed inconduit 4 and fed to the fluid receiving means 51 via the inlet 54thereof. The balance of the water was added to the receiving vessel 9.Only 92 percent of the ammonia reactant was introduced into the reactionvessel 1 via the inlet 53 of the fluid receiving means 51, the balancebeing added to the liquid product in the receiving vessel 9.

The pressure drop across the reaction vessel was held at about 20 psig,the reactants being introduced at a rate such that the retention time ofthe reactants within the vessel 1 was about 0.1 second.

In the cooling tower 6, the liquid leaving the reaction vessel 1 at atemperature of about 107C. was quenched by contact with about scfm airper ton of liquid so as to be cooled rapidly to a temperature of about43C.

The product was a liquid of 20-20-0 grade having a pH of about 6.5 withan N:P O ratio of 1:1. About 51 percent of the product was ammoniumpolyphosphates. Example 2 The reactants were the same as in Example Iand the process conditions were the same except in that the reactionvessel 1 was modified so as to have a separate inlet for the nitric acidreactant, the inlet 54 of the fluid receiving means 51 being fed withwater only and the nitric acid being fed instead to an inlet in thecolumn 72, this inlet being connected to a spray nozzle positionedwithin the topmost cylindrical section 60 of the column 72.

It was found that by using such a modification reaction vessel, asubstantial proportion of the phosphoric acid reactant had already beenammoniated before meeting the nitric acid reactant. As a result, theproduct, although also a 20-20-0 grade liquid, had an ammoniumpolyphosphates content of about 56 percent. Thus the delayedintroduction of the nitric acid into the reaction mixture substantiallyreduced the hydrolysis of the polyphosphoric acid components of thephosphoric acid feedstock as compared with the results of the procedureof Example 1, wherein even the brief contact that occurred between theacqueous nitric acid entering the vessel 1 through inlet 54 and thephosphoric acid entering through irilet 52 was sufficient to accomplishsubstantial hydrolysis of the polyphosphoric acids before these werestabilized by ammoniation.

lclaim:

l. A process for the production of a near neutral liquid'solutioncontaining a mixture of ammoniated nitric, phosphoric and polyphosphoricacids which comprises continuously:

a. intermingling in a reaction chamber water, am-

monia, nitric acid and phosphoric acid containing polyphosphoric acidcomponents for ammoniation of said acids therein under highly turbulentconditions at a temperature within the range of 220 to 280F to form areaction mass comprising steam and a liquid solution of ammoniatedphosphoric acid, ammoniated polyphosphoric acids, ammoniated nitric acidand water, the amount of ammonia fed to the reaction chamber being lessthan that required for neutralization of acids;

b. withdrawing the liquid solution and steam from the reaction chamber;

c. transferring the liquid solution and steam to a cooling tower whereinsaid liquid solution flows downwardly;

d. quenching said liquid solution in the cooling tower with an upwardlyflowing countercurrent air stream to cool said liquid solution to atemperature within the range of to [50F and to remove steam and watervapor therefrom; and

e. adding ammonia to the quenched liquid solution in an amountsufficient to produce the near neutral liquid solution.

2. The process of claim 1, in which the reaction chamber is a tubularreactor and said nitric acid stream is introduced into said tubularreactor at a point downstream of the point of introduction of theammonia phosphoric acid and polyphosphoric acid components.

3. The process of claim 1, in which the said reactants are caused toreact in said reaction chamber within a period of 0.1 second to 15minutes.

4. The process of claim 1, in which water is added to the liquidreaction product after said quenching thereof.

2. The process of claim 1, in which the reaction chamber is a tubularreactor and said nitric acid stream is introduced into said tubularreactor at a point downstream of the point of introduction of theammonia phosphoric acid and polyphosphoric acid components.
 3. Theprocess of claim 1, in which the said reactants are caused to react insaid reaction chamber within a period of 0.1 second to 15 minutes. 4.The process of claim 1, in which water is added to the liquid reactionproduct after said quenching thereof.